The application relates generally to power-assisted vehicle steering mechanisms, and more particularly to safety aspects of power-assisted vehicle steering mechanisms.
Modern vehicles are equipped with electronic safety systems, which provide assistance to a driver. In addition to the widespread ABS (anti-lock braking system) and airbag system, ESC (Electronic Stability Control) has assumed great importance. An ESC system is capable of individually controlling and braking each wheel of a vehicle and of preventing over-steering or under-steering while considering measurement signals from several sensors. An ESC system can automatically perform active steering interventions and superpose them on the steering actions of the driver.
An increase in internal friction within an EPAS (Electric Power Assisted Steering) geared motor due to wear or contamination can lead to malfunctions in the EPAS system or the ESC system. The system could incorrectly interpret the internal friction fault as originating from external driving conditions, and as a result, generate incorrect controlling instructions to the EPAS or ESC system.
Further, present systems would benefit from detection of inadequate tire traction, caused by external factors, such as ice, water, or oil on the road surface
Although current EPAS or ESC systems are equipped with a number of sensors, the sensors may not reliably identify inadequate tire traction or high internal friction conditions within the steering mechanism. Further, the integrated microprocessor system has limited computing and storage resources, leaving little computing capacity available for the detection of such conditions.
A known solution provides a system and method for determining excessively low tire traction and increased internal friction within the steering mechanism of a vehicle. Here, the angular acceleration of the steering wheel and the speed of the vehicle are detected, and the angular acceleration is compared with stored minimum or maximum tabulated threshold values for the respective traveling speeds. Such a system is suitable only for slowly proceeding, low-frequency events but does not perform satisfactorily during event sequences of higher frequency.
Moreover, the computation-intensive data processing methods of EPAS or ESC systems lay claim to limited resources, leaving little capacity available for additional computing tasks.
It would be highly desirable to have a method for determining increased internal friction within a steering mechanism of a vehicle, even during high-frequency event sequences while utilizing minimum system resources.